TransferTests.cs

    [TestFixture]
    public class TransferTests
    {

        [Test]
        public void AmountTransferredFromPayerToPayee()
        {
            // initialise accounts
            double payerBalance = 0;
            double payeeBalance = 0;
            
            // credit payer with funds to allow transfer
            payerBalance += 100;

            // transfer 50
            payerBalance -= 50;
            payeeBalance += 50;
            
            Assert.That(payerBalance, Is.EqualTo(50));
            Assert.That(payeeBalance, Is.EqualTo(50));
        }

    }